21708971 has 8 divisors (see below), whose sum is σ = 22278720. Its totient is φ = 21143808.

The previous prime is 21708943. The next prime is 21708979. The reversal of 21708971 is 17980712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21708971 - 2¹⁰ = 21707947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21708979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9755 + ... + 11771.

It is an arithmetic number, because the mean of its divisors is an integer number (2784840).

Almost surely, 2^21708971 is an apocalyptic number.

21708971 is a deficient number, since it is larger than the sum of its proper divisors (569749).

21708971 is a wasteful number, since it uses less digits than its factorization.

21708971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2293.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 21708971 is about 4659.2886796162. The cubic root of 21708971 is about 278.9628766612.

The spelling of 21708971 in words is "twenty-one million, seven hundred eight thousand, nine hundred seventy-one".